(1) Field of the Invention
The present invention relates to management of content data and a method for the management, in which a content having copy control information is moved, namely transferred.
(2) Description of the Related Art
Currently, in the field of broadcast satellite (BS) digital broadcasting and terrestrial digital broadcasting, aiming to protect copyrights of broadcast contents, broadcast waves even for free broadcasting are scrambled to implement, in principle, a copy control of “copy-one-generation” for the broadcast contents.
A signal for the copy control is multiplexed together with compressed content data, such as image data and audio data, in order to be sent as a transmission control signal. The transmission control signal has a program map table (PMT) storing a digital copy control descriptor that includes digital copy control information (digital recording control data), and the digital copy control information controls a copy generation of the broadcast content as shown in FIG. 1.
Referring to FIG. 1, digital copy control information “10” represents “copy-one-generation” (hereafter, referred to as “copy-once”). This means that, when a digital broadcasting content has the digital copy control information “10”, the content can be copied one time only (copy-once). Further, when the digital copy control information is “00”, the content can be copied without any limitation (copy-free), and when the digital copy control information is “11”, the content cannot be copied (copy-no-more).
Due to the introduction of the “copy-once” control into the digital broadcasting, for example when a copy-once digital broadcasting content is received using a digital video recorder carrying a hard disk drive (HDD), a recording type digital versatile disk (DVD), or the like, and then recorded (copied) onto the HDD or the DVD in the digital video recorder, the recorded content is accumulated as “copy-no-more” so that the content cannot be further copied. Note that even after the content is accumulated as “copy-no-more”, it is not necessary to change the value “10” of the digital copy control information in the digital copy control descriptor.
Also note that the accumulated content whose status has been changed from “copy-once” to “copy-no-more” cannot be copied, but can be moved, namely transferred. For example, the content can be transferred to an external recording medium enabling copyright protection such as Content Protection for Recordable Media (CPRM). Note that, however, the content can be moved to only a single recording medium digitally connected to or built in the digital video recorder. In case that the content is moved to such a recording medium which is connected via a high-speed digital interface, it is necessary to conform regulations of Digital Transmission Content Protection (DTCP).
Note that when the content has been moved, the content recorded in the move source, namely the HDD or the DVD, should be deleted or disabled from being reproduced. This means that when the move is complete, the contents must not be available both in the move source and the move destination at the same time.
Meanwhile, such introduction of the “copy-once” control has a risk of losing user's convenience in the following case. The case is when the recorded content (former copy-once) used to be a high-quality content, but it is converted into a lower-quality one, by being lowered its quality, namely image and sound quality of the content, in order to be moved. After the content has once been converted into the low-quality content and moved, the content is reproduced only as the low-quality content even if the content is moved backwards to the move source. This means that those who wish to watch or listen to the content cannot play the content with the original high quality.
More specifically, regarding the move accompanied with the conversion, there is a case that the copy-once content in the move source is a high-quality High Definition (HD) image and recorded on HDD or Blu-ray Disk, but the move destination is a medium having a small recording capacity, such as a DVD or a memory card, and the content is converted into a low-quality Standard Definition (SD) image to be moved. However, the content converted from the HD image to the SD image is generally not able to be converted backwards from the SD image to the HD image, so that it is impossible to restore the original high-quality HD image, since the content has been compressed and encoded with a lower recording rate.
To address the above problem, Japanese Patent Laid-Open No. 2002-251819 publication for an invention entitled “Digital Information Recorder, Reproducing Device and Transmitter” discloses that, after a copy-once content is received and recorded, the disclosed technology controls to move and temporarily copy the content by managing its duplicable time period, playable time period, and the like by a clock. Thus, after the copy-once content is received and recorded, the content can be copied to another recording medium within a predetermined time period. Therefore, even if the high-quality content has been received and recorded, and then outputted as a low-quality content to another recording medium, the disclosed technology enables the user to play the content with the original high quality.